[sudosysgen]

Hahaha.

NASA is very strongly tied into the US military. NASA projects are bid on by US military contractors, and NASA flies military airframe all the time. NASA pretty much is an arm of the US MIC, in a way that the ESA or the CSA aren't.

And also, the Soviet space program was also openly tied into their military, and that wasnt an issue.

The real reason is that the US wants to make everything hard and expensive for China, due to perceiving them as a competitor. It's just not interested in cooperation.

As for violation of international law, neither the US nor the Soviets cared about it. It's just politics.